"Parents need to love their children."
Translation:Los padres necesitan amar a sus hijos.
'Ninos' implies any children and 'hijos' is specifically their children. Though I would have thought the 'sus' would qualify it. That's my best guess anyway.
Ditto, especially since up to this point "ninos" has been used as "children"
Some idiosyncrasy of the language they teach us here in this way I suppose. Hijos antes de ninos... vive y aprende.
Why is it amar and not amor? Both nouns are masculine. Los padres and Los hijos
I don't disagree with the underlying meaning of your translation, but in a literal sense, necesitar is "to need" and tener que is "have to." So there is the very slightest difference in nuance. What I am saying is that necesitar is better for a language course like this where you are given a sentence out of context, but if you were translating a paragraph it might be a fine translation depending on context and voice.